This disclosure relates generally to food dispensing machines, and more particularly to frozen carbonated beverage machines.
Food dispensing machines, such as frozen carbonated beverage machines produce a frozen beverage by freezing a mixture of water, syrup concentrate and carbon dioxide in a mixing, or freezing, chamber. The freezing chamber is typically surrounded by a coil that contains refrigerant to cause freezing of the mixture inside to a desired level of consistency. The mixture is removed from the inner surface and mixed by a rotating shaft driving a scraping/mixing member attached to the shaft. The frozen mixture consistency is controlled by any of a number of methods that turns on the refrigeration to freeze and turns off the refrigeration when the mixture reaches the desired consistency. A consumer can then dispense the product as desired through a dispensing valve.
The water and syrup concentrate are usually supplied to the freezing chamber via flow controls to maintain a precise flow rate of liquid even as the inlet and/or discharge pressures vary. The carbon dioxide gas flow rate is controlled via a regulator and orifice. The volume of the product dispensed from the mixing chamber is defined as “overrun.” A beverage that doubles its volume when it is dispensed from the mixing chamber in a semi-frozen state is defined as having an overrun of 100%. Generally, the more carbon dioxide that is added to the mixing chamber, the higher the overrun. It is desirable to be able to control overrun so that the consistency of the product can be maintained.
The regulator controls the pressure of gas input to the freezing chamber, but the discharge pressure from the regulator can vary and result in fluctuations in the gas flow rate. One method to mitigate this fluctuation is to increase the inlet pressure to the regulator until the normal discharge pressure range from the regulator is low enough as not to affect the flow rate. However, pressure regulators can drift, resulting in variations in the discharge pressure. Further, the carbon dioxide content of the finished product often needs to be adjusted to produce the desired drink consistency.